{Core} Discard tenant_id in get_token

[jiasli]

Description

azure-keyvault-keys==4.5.0b5 made a breaking change for authentication:

• [Key Vault] Add support for multi-tenant authentication azure-sdk-for-python#21290

It uses azure-identity's new multi-tenant authentication API get_token(tenant_id=...) from

• Update Multi-Tenant support to incorporate Arch Board Feedback azure-sdk-for-python#20940

However, the current authentication of Azure CLI cannot handle get_token(tenant_id=...) because a credential inherits from an MSAL application, so tenant_id is fixed during the initialization of a credential/MSAL application. In order to support get_token(tenant_id=...), the MSAL application must be created during get_token, which requires a total overhaul of the authentication mechanism.

As currently Azure CLI can't automatically get an access token from another tenant for keyvault data-plane operations, we discard tenant_id in get_token so that there will be no behavior change while supporting azure-keyvault-keys==4.5.0b5.

Also see: #20880

[yonzhan]

Core